There was a time not long past when refrigerants, commonly used in large systems for warehouses and supermarkets, such as dichloro-difluoro methane, known in the trade as R-12, cost less than one dollar per pound and lubricants of the type employed with R-12 cost less than a dollar per gallon.
Subsequently it was found that the concentration of stratospheric ozone was declining, especially in the Antarctic regions. Many scientists believed that R-12 and similar fully substituted chlorfluorocarbons (CFC's) were escaping from refrigeration systems and from industrial processes which employed them and were migrating to the stratosphere where the chlorine atoms in these chemicals attacked and destroyed the ozone present there.
Governments decreed that the production of such chemicals stop. To satisfy the demand for refrigerants for comfort and process and food cooling and freezing, a group of chemicals which employed fluorine but had no chlorine was developed (-FC refrigerants). These new -FC refrigerants cost ten or more times greater than the prebanned price for the old CFC refrigerants. The old low cost oils were believed to not work correctly with the new -FC refrigerants and new oils were developed. Instead of costing only a few dollars per gallon, the new oils such as polyolester (POE) chemicals cost much more.
It was found that the greater the mass of refrigerant required to be charged into a system to make it function correctly, the greater the volume of lubricant was needed to satisfy the requirements of the compressor.
Therefore efforts were directed to designing systems which employed less refrigerant, thereby requiring less of the new lubricant and thus providing the dual benefit of reduced aggregate cost for both as well as sharply reduced risk of loss in the event of a serious refrigerant leak.